For the duration of the DDP [Johns Hopkins University Doctoral Diversity Program], I am conducting research full-time in Dr. Sandra Gabelli
’s lab, where one of my projects involves studying NUDIX hydrolases, a superfamily of enzymes known for their ability to remove mutagenic nucleotides from the nucleotide pool. They are named after their shared ability to catalyze the hydrolysis of nu
phosphate linked to a moiety X, hence the name NUDIX. Many NUDIX hydrolases have cellular roles ranging from the degradation of mRNA and processing of ADP-ribosylation to the removal of mutagenic nucleotides from the nucleotide pool. Though a highly conserved signature motif of 23 amino acids, GN1
U, known as the NUDIX signature sequence, allows us to identify these enzymes, more information is necessary to classify these enzymes into families.
Previously, the NUDIX family represented by NudI was identified to be nucleoside triphosphatases with a preference for pyrimidine deoxynucleoside triphosphates. Recent studies have shown that NudI preferentially hydrolyzes geranyl pyrophosphate [GPP] instead of a nucleoside containing metabolite. I am characterizing an atypical NUDIX family, represented by NudI whose preferred substrate, geranyl pyrophosphate, lacks a nucleotide in comparison to the archetypical substrate. Using the conformational changes that NUDIX enzymes undergo upon substrate binding, product release and inhibitor binding will allow me to establish the rules of recognition. The characterization of NudI as a hydrolase of GPP, with its structural determinants of specificity and inhibition, is a step toward identifying the pathway it is involved in and establishing the rules for classifying NUDIX enzymes into families.